Computed Radiography (CR) is a well established method of radiographic imaging used in the health care environment. The CR system involves exposing a storage phosphor contained in a cassette to x-radiation of a body part of a person to produce a latent radiographic image in the storage phosphor. The cassette is presented to a storage phosphor reader where the storage phosphor is extracted from the cassette, scanned (read) with a stimulating radiation beam to produce a stimulated radiation image which is converted to an electronic (digital) image which can be stored, displayed, transmitted, or output on film. After the latent image has been scanned, the storage phosphor is erased to remove noise and any residual image, and the storage phosphor is replaced in the cassette ready for reuse.
The scanning system typically uses a laser to energize the storage phosphor. Light energy is released from the storage phosphor and collected using multifaceted, mirrored surfaces, which direct the light energy into photodetectors that amplify the signal. The scanning operation is very sensitive to vibration and impacts, which cause relative movement between the laser and storage phosphor, between the storage phosphor and the light collector, and vibrations around the constant velocity drive system, which moves the storage phosphor past the scanning laser. Such vibrations can result in undesirable image degradation which can affect the diagnostic quality of the radiographic image. In a known storage phosphor reader, vibration isolation is accomplished by separating the scanning assembly from the outer frame and from an upper cassette handling assembly by supporting the scanning assembly separately on the floor.
U.S. Pat. No. 4,833,325, issued May 23, 1989, inventors Torii et al., discloses an image readout apparatus in which stimulable phosphor sheets are transported along a horizontal path through an image readout system. Vibro-isolating light shield members are interposed between the image readout mechanism and a casing, which are individually supported on a floor. Vibro-isolating members are also disposed between a conveyor system for delivering a stimulable phosphor sheet and an optical system for applying the stimulating light to the stimulable phosphor sheet.
U.S. Pat. No. 4,417,260, issued Nov. 22, 1983, inventors Kawai i.e. al., discloses an image scanning system in which the optical components for scanning a stimulating light beam across a recording medium and the mechanical components for moving the recording medium through the system in a horizontal direction are all mounted on a single frame which in turn is mounted by way of a vibrating insulator on an outer frame structure.
U.S. Pat. No. 5,440,146, issued Aug. 8, 1995, inventors Steffen et al., discloses a radiographic image reader wherein a photoreceptive medium is transported horizontally through the reader and an optics module is supported on a support stand by kinematic mounts.
U.S. Pat. No. 6,739,768 B2, issued May 25, 2004, inventors Johnke et al., discloses an apparatus for processing photographic material horizontally transported through the apparatus. A housing and a processing station are each independently mounted through their own oscillation-damping connection to a common support base.
None of these patents address the problem of vibration isolation in apparatus in which a storage phosphor is vertically transported through a scanning and erase process or the problem of locking the scanning assembly to a cassette handling assembly during transfer of a cassette between such assemblies.